Devices are known in the prior art for regulating the volume rate of delivery of a fluid from the discharge side of a pump by intermittently opening and closing a fluid flow interrupter in communication with the discharge and suction sides of the pump, with a non-return valve disposed downstream of the communication between the flow interrupter and the discharge side of the pump and communicating between the discharge side of the pump and the load. U.S. Pat. No. 3,316,846 is a device of this type which uses a rotating cylinder for opening and closing a line to return the fluid to a pump reservoir. However, the cylinder is hollow and the fluid is fed outwardly through the cylinder and into a return line.
U.S. Pat. No. 1,990,263 teaches a similar valve arrangement, downstream from a pump, on which raised ribs on a rotating shaft open and close access to a return line. There is only a single outlet directing the fluid from the pump toward the shaft.
German Offenlegungsschrift No. 2,519,366 teaches a similar arrangement with a single discharge with a shaft having a raised rib thereon which opens and closes the opening as the shaft rotates.
U.S. Pat. No. 2,729,167 and French Pat. No. 370,319 also show rotating valves.
All of these known devices however are suitably only for use at low pressures. At high pressures the leakage losses as well as noise production reach intolerable values.